This was discussed a couple of times earlier. But then, so was DRM and ebook prices.

Ads have been in books in the past , contrary to myth. If ads can be done in a tasteful, non-intrusive fashion, and if the economics justify it, they will be in ebooks

Did you just use the word tasteful with respect to advertising? It will be tasteful until the cognitive behaviorists in the marketing departments start using all their tricks to divert reader's attention away from reading. I can't wait for my first flashing text hot singles advertisement on my Kindle. Great.